Which is better for a DBA (Swarm); powered subs or unpowered?

cleeds-The price for that smooth, even, neutral bass is that your bass will be monophonic. 

noble100-Even though all 4 subs are run in mono, the bass will still be perceived as stereo.

Right. And thank you, Tim.

The issue of is the bass stereo or not is beside the point. The simple fact of the matter is DBA bass is exactly as focused and localized and 3D as anything and everything else. This from a guy who will put his system up against anyone's in the area of imaging. Any time. No problem.

Recording after recording I'm hearing bass that is never once anything less than seamlessly integrated with the sound field. Each awesome deep drum whack on Jennifer Warnes Bird on a Wire has its own unique location, reverberation and resonance. Its felt exactly as a drum that size would be, as coming from one spot then energizing the whole acoustic space.

Please note I say "acoustic space" not room. Because if I say room people will think I mean my room. Wrong. I'm talking the acoustic space where the recording was made. My system and in particular the DBA part of it effectively take my room out of the equation. My room for all intents and purposes is not there. You for all your ears are telling you are not in my room. You are in acoustic space. 

Duke explains the tech better than anyone. I can only relate what I'm hearing. What others have heard. You cannot be more wrong than to say DBA sounds like mono. It may very well be mono. But it does not in any way shape or form sound mono. So maybe that is hard to understand. Oh well. It is what it is.

I will say this though. This will be a whole lot easier for people to understand if the ones who haven't ever experienced it and therefore really have no idea what they're talking about would wait to comment until they can correct such a glaring weakness in their approach.

Ieales wrote: 

" DBA proponents are not charlatans, but neither are they correct as the the ability it to produce time coherent bass. " 

Arrival time coherence in the bass region is not critical, but decay time coherence in the bass region is. 

The ear is incapable of even registering the presence of bass energy from less than one wavelength. And the ear is incapable of registering pitch from less than several wavelengths. This from a Journal of the Audio Engineering Society paper which I no longer have access to. 

So the ear simply does not have enough time-domain resolution in the bass region to detect arrival time differences of a few milliseconds. 

So let’s look at the decay times. The longer a sound lasts, the louder it is perceived to be. So bass frequencies which take longer to decay sound louder. 

Also, since speakers + room = a "minimum phase" system at low frequencies (according to both Floyd Toole and Earl Geddes), when we know the frequency response, we know the time-domain response. Thus is it the peaks which take longer to decay into inaudibility. This implies that the frequency response is particularly important at low frequencies. 

Which indeed turns out to be the case. If we examine a set of equal-loudness curves, we see that they bunch up south of 100 Hz, such that a 6 dB change at 50 Hz is perceptually comparable to a 10 dB change at 1 kHz. This in turn implies that improvements in the frequency response in the bass region pay subjectively large dividends. 

In other words I believe that a good distributed multi-sub system addresses the issue that matters the most to the ears; namely, the in-room frequency response. 

Ieales again: "By FAT I mean that unless time correction is implemented the separate sub signals will arrive spread over several milliseconds... 

"IMO, it’s as unlistenable as MP3... 

At RMAF 2017 we displayed using a distributed multi-sub system in one of the standard (small) hotel rooms. An industry veteran cable manufacturer, with several decades of experience, handed us his thumb drive and asked us to play a recording of Fanfare for the Common Man. When it was over, he told us that was the most natural rendition of the tympani he had ever heard in any room at any audio show. He said it sounded just like what he heard when he went to a concert. 

(Incidentally in my experience the term "fat" is normally associated with a frequency response peak and its attendant long decay time, so it IS a time-domain issue - but applicable to the DECAY behavior, not the ARRIVAL TIME behavior. Our ears cannot react fast enough to hear "fat" in the arrival of bass energy).   

So I’m going to go out on a limb and claim that Ieales’ statement that a distributed multisub system is "as unlistenable as MP3" is an exaggeration. If he wishes to prioritize arrival time that is fine with me, we have a difference of opinion on that subject. 

Duke

I (hesitantly) decided to go with the Swarm after reading through the postings here (in particular from millercarbon and noble100) and other sources. These are very knowledgeable people with real world experience.

Now with all 4 subs singing, bass is extremely present, dynamic, fast and very clear. Everything I read in the posts were true and not exaggerated.

Indeed. 

I think I’ve decided to go with the Dayton SA1000 and two 10” or 12” passives; any suggestions on a decent quality sub for ~$300??? I’ve heard someone on this site recommend the Dayton Audio subwoofer kits on Parts Express ($265 for the 10” Ultimax, $311 for the 12”); has anyone heard them, or anything else in this price range?

Mine are the Morel 10". https://systems.audiogon.com/systems/8367
Two are the Parts Express sealed kits. The other two are the same kit, expanded vertically to increase volume because they are ported. I would not hesitate to just go with whatever Parts Express sub/cabinet kit you like. Just be sure to pay attention to impedance especially if you will be running multiple (4) off one amp.

@millercarbon thanks for the details -- you have a beautiful system, but I couldn't tell from the photos if you were using both powered and unpowered. Do you run your powered subs through the sub amp, too? If so, what is the advantage?

Look real close at image #9 you will see a dirt cheap POC IC going from the Melody to the Dayton amps. Its fake gold with a spring and white and red o-rings. A real POC. Immediately to the left of it on the Dayton is a clear plastic IC with a silver RCA with 3 black rings, and just below it you can just barely make out the other one with 3 red rings. The signal from the Melody comes into both Dayton amps, then uses the Daytons built-in bypass to connect to the additional Talon Roc powered sub.

So its "through" the Dayton but Daisy-chained not actually running through any amplification, EQ or level circuits. 

Some subs (I think REL is one) allow you to wire them in a way that reduces the burden on the main amp to cover frequencies below a set cutoff, like 80Hz. Does anyone know if that is possible with the Dayton?

This is another one where you'll hear guys who love tech more than music tell you all the wonderful tech reasons to do this. There are wonderful tech sounding reasons for doing all sorts of things that don't really work out well in practice and this is one of them.

The idea is supposed to be that by relieving the amp and speakers of the majority of energy which is bass that you will get improved detail and a greater sense of ease, and on and on, probably cure cancer, almost certainly cure cancer if a REL is in there somewhere. Amazing sub, REL. Don't even need a DBA all you need is a REL. Yeah I am being super sarcastic.

Because, always left out of the equation is the detail you lose running that signal through the crossover circuit, and extra interconnects, and how its all affected by the quality of the power and on and on and on. They conveniently leave all that out.

What they also leave out and this one is even bigger, is the whole reason we're doing DBA is to take advantage of the superiority of having a lot of different bass sources. Of which your two main speakers are two additional sources. So you shoot yourself in the foot with the bass, add extra stuff in the signal path, don't get the improvement they promised, and actually make the bass worse in the process.

cheeg- sorry, my pager battery died-

Starting with $1000, am I better off buying two used powered subs, three less expensive used powered subs, or a subwoofer amp (eg Dayton SA1000) and two (less expensive) used unpowered subs? What is the advantage of having a discrete subwoofer amp?

Either way will work and depending on your situation and deals you might come across which is better could go either way. Either one will allow you to start small and build. So good question.

That said, the Dayton approach has several advantages:

Reliability- powered subs typically use plate amps that are not all that reliable. Dayton and Parts Express are more reliable.

Quality- having the amp separate from the speakers makes it easier for you to select higher quality subs. With powered subs a little bit of each purchase goes into the amp. You’re buying amps over and over again. So you can get a little more speaker for your money this way. Also if you DIY you can get a lot more speaker this way.

Flexibility- The Dayton has just the EQ, level, filter, boost, and phase control that you need. Most powered subs will have these too. But buying on a budget maybe not all or quite as good. With the Dayton no worries. Also with the Dayton when you get more subs you’ll be able to experiment with connecting subs in series or parallel to change the impedance which changes the sound, which turns out to be a pretty good advantage.

Convenience- With the Dayton you set levels all at once. One interconnect. One power cord.

Main thing to keep in mind when going this route is the unbelievable benefits of a DBA really have more to do with the number of subs than anything else. So you will probably get better results faster with 4 cheap subs than a Dayton and one or two better subs. In the long run though as long as you are sure to complete this with 4 (or more- I have 5 and the 5th really did make it better) then I think the Dayton is the way to go.

Maybe even bigger thing to keep in mind is you just can’t imagine how good the bass will be. Its something you have to experience to believe. Maybe not even then. Had mine a year now and it still amazes me.

Oh, and doing one does not rule out the other. You can do both. Have you seen my system?
https://systems.audiogon.com/systems/8367